| Summary: | In the medical field, one of the applications of DEP is the size based separation of cells or particles. However, the conventional method to fabricate microfluidic devices are costly, utilize harmful chemicals and time-consuming. Furthermore, rapid prototyping is necessary by researchers designing such devices to test its functionality. With the interest in additive manufacturing growing, this had led to exploration of additive manufacturing of the microelectrodes which is the key component in such devices.
Inkjet printing is a method which is simple, low-cost and is able to achieve rapid prototyping of the electrodes. This report highlighted the feasibility of utilizing DEP in the printed microfluidic device by discussing the effect of voltage and frequency on 6μm and 10μm polystyrene beads as well as a mixture of both particles. The prototypes were made using various equipment and materials readily available in the microsystems lab and it could be easily fabricated within 24 hours.
From our experimental results, a stronger magnitude of DEP force in the same direction could be observed when voltage is increased, resulting in a stronger attraction or repulsion of 10μm polystyrene beads. However, further increment above 12V would cause the electrodes to corrode as observed from the darkening of electrodes. By varying the frequency, changes could be observed near the crossover frequency of 5 kHz, where attractions were observed above 5 kHz and negligible effects below 5 kHz on the 10μm polystyrene beads. Electrodes were observed to be corroding at low frequency (below 2 kHz) despite having a low voltage because AC behaved more similar to DC, which results in a faster rate of electrolytic reaction. As DEP force has a cubic relationship to the radius of particles, 6μm polystyrene beads were not trapped during the experiments.
In conclusion, inkjet printing is a cheap, non-toxic and a quick method to fabricate functional electrodes of microfluidic devices and this report proved the application of inkjet printing in the fabrication of microfluidic devices to be feasible and beneficial to the researchers in the field of microfluidic, lab-on-a-chip or biological science.
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